Hearing. While I love music, I love not walking off a subway platform even more.
It’s quite surprising to me that so many people can definitely decide which they’d give up. I honestly can’t decide, and that’s only based on two of my favorite things to do: listen to music and watch movies. No music would be horrible, so losing hearing is out. But at least half of the movie-watching experience is visual (much more so in the case of silent movies), so losing sight is out too. I just couldn’t possibly decide; neither activity (to say nothing of the difficulties of just getting along in the world without one of these senses) is more important to me than the other.
In other words, neither. Which is cheating, I know. But I honestly can’t decide.
Definitely hearing. I already know a bit of sign language and it’s easy to learn when you really apply yourself. I’m also a visual artist, so I wouldn’t be able to lose that.
All the people who said that you can’t have normal human relationships or communicate if you’re deaf need to come hang out at my work. We have a lot of secondary education students learning to teach special needs people, the deaf and the hearing communicate with no problems at all.
I’m at a high risk for going blind in several ways, and that scares the crap out of me.
Hearing. If there was no chance of regaining either senses then I would choose hearing. To be honest, it would be harder to live without sight. I would be ‘more disabled’ if I was blind. At least with sight and deafness, I would still be able to walk, read, and do other things of that nature. And I could always have a hearing aid. I think that biotechnology for the sense of sight is a long way off.
You might be interested to know that with blindness, your sense of hearing actually improves and thus your musical abilities. Just think of the great music of Ray Charles and Stevie Wonder.
Always with the hard questions… 
I would say that I would prefer to lose my hearing. I have a friend who has been deaf from birth, and she’s a high-achieving, athletic, travel-loving uni student. I don’t think she could do what she loves if she were blind, not deaf.
Myself, I love reading, I learn things visually, I love to look at beautiful works of art and so on. I would miss music and the sound of people’s voices, but to lose my sense of sight would devastate me too much.
Even though I have partial hearing loss, and I am proud of my excellent eyesight, I would take loss of sight over hearing. I think auditory communication is mnore important than the advantages sight offers us. As is was stated above, blind people can function just fine. So can hearing-impaired persons as well, so I guess its a matter of preference.
I’d say hearing, because my life and joy is the computer. It’ll probably be my job, too, in five or six or more years.
This is an easy one for me.
If I had to lose my sight or my hearing I would choose to lose my hearing.
My five year old son was born partially deaf so it would give us something else in common. 
I’d rather lose my sight; I judge too quickly based on what I see as it is, frankly. Music and people’s voices are a far more important and basic connection to me. I’m glad to save pictures, but some of my most prized memories are voicemail messages and mixed cd’s/tapes.
I know some deaf people who sign amazingly and get on very well in a world that favors the hearing population - but still. I don’t have that fortitude. And if it meant not having to drive 19 miles each way to work ever again, somehow I’d survive!
I wouldn’t mind losing my hearing, because I could still remain independent. Losing my sight would require some dependence on others, and that would make me INSANE.
Having recently and inexplicably losing partial hearing in one ear last summer ( 55% loss in my left ear with constant ringing.) I have to say it hasn’t been all that bad.
All my auditory feed is through my good ear and crowded situations cause auditory chaos and general confusion, but I sleep like a rock.
Losing either would suck, but losing my sight would suck more.
Hey forget that Daredevil bullshit about blind people “seeing” with their ears. Forget missing TV or movies or whatever. Try missing being able to drive to the supermarket and buy groceries by yourself. Try missing going anywhere without a laborador retreiver and a white cane.
If you think blind people function “just fine”, spend one entire day blindfolded and another day listening to white noise on an iPod and then decide.
My first instinct was “deaf,” but then I thought about it and realized I’m firmly in the “blind” camp. I’ve learned a lot about Deaf culture and the experience of being deaf from my sister (speech pathology student). I read a bunch of issues of “Deaf Life” and got the impression that there’s a much greater feeling of being cut off from the world than the blind people I know seem to feel. Losing reading and crossword puzzles would be rough, but these days, there are many more accommodations for that than there used to be.
Sight, without a doubt. I would miss seeing, but going deaf would cost my livelihood and the most important thing in my life - playing music.